Abstract:
This research was to study the appropriate conditions for using trichloroisocyanuric acid (TCCA)as the disinfectant for swimming pool. The amount of TCCA required to release 1.00 - 3.00 mg/L offree residual chlorine (standard for the swimming pools) was 3.00 and 15.00 mg/L for the tap water andthe synthesis, respectively. The addition of TCCA was controlled by oxidation reduction potentiometerat 710 - 750 mV. The residual chlorine of 0.5 mg/L from TCCA killed 93% of E. coli and faecalcoliforms. The effects of time, temperature and various parameters were studied. The results showedthat the alkalinity were increased while the residual chlorine decreased with time, temperature had noeffect on all parameters. Studies of TCCA effectiveness used in swimming pools in Thailand, found thatpH value was as low as 3.0. At this low pH level, teeth corrosion of swimmers was found, thereforeTCCA usage needed to be controlled for maintaining the pH level. Sodium bicarbonate, sodiumcarbonate or sodium hydroxide should be used to bring the pH up to 7.2-7.5. In case of high cyanuricacid(CA) concentration, HOCl concentration will be decreased, resulted in the ineffectiveness ofdisinfection due to the HOCl lock phenomenon. Therefore after pH adjustment, the sodiumhypochlorite solution should be used instead of TCCA until CA concentration complied with thestandard.